Pitney Bowes
MapInfo Pro™ Monthly Journal
Enhanced Display Quality with Underviews

Mahima Mapinfo Pro Advanced introduces a new capability to enhance the display quality of raster data in your Map windows when you zoom in past the base resolution in the stored raster data file. The new visualization options are referred as "Underviews". This capability was introduced in the 15.2.2 x64 patch release as a "Technical Preview" feature and will be formally released as part of the upcoming 1v6.0 release.

When you zoom in on a raster file such that Map zoom level goes beyond 100% for that raster you begin to exceed the original resolution of the raster. When this occurs there is no more data in the source raster to display on the screen so the original data pixels just get replicated on the screen which causes the pixels to become obvious and the visual quality to decrease. This behavior results in pixelated looking images when you zoom in too far for the data resolution. To address this quality issue, MapInfo Pro Advanced introduces some new display resampling methods to enhance and smooth data when you zoom in beyond the base resolution of the source file. When enabled, these new display resampling methods will maintain a smooth and high quality appearance to the raster data even once you zoom in beyond the resolution of the individual pixels.

How does it work?

Underview data is generated from the original base level raster data as needed, using one of the available interpolation methods. The data is never stored in the original raster file but is instead generated "on the fly" when data is needed for display or by some processing operation at a higher resolution than stored in the file. There are currently 5 interpolation methods available for generating new data. Regardless of the method chosen, the spatial coverage of the underview data will be exactly equal to the base level data such that valid cells will be re-interpolated and null cells will remain unchanged.

Standard Rendering Enhanced Rendering New resampling Methods
Standard Rendering Enhanced Rendering New Resampling Methods

Above is are some example images which show the difference between Standard rendering, Enhanced rendering using smoothing and Enhanced rendering using new a new resampling method. The new resampling method is Bi-Cubic(global) and is applied on Continuous elevation data.

The following resampling methods have been provided.
  • NEAREST NEIGHBOUR: Raster cells are assigned from the closest cell in the base level raster.
  • BI-LINEAR: Linear interpolation is performed between adjacent cell centres.
  • CUBIC SPLINE (Akima): Applies Akima spline interpolation over a local region (we consider this an experimental method).
  • CUBIC SPLINE (Local): Applies cubic spline interpolation over a local region of cells.
  • CUBIC SPLINE (Global): Applies cubic spline interpolation over a large region of cells.
Interpolation Methods that are best for Specific Data Types:

Colour Field or Colour Band Bi-Linear Interpolation
Classified Bands Nearest Neighbour
Image Palette Nearest Neighbour and Bi-Linear
Continuous All

While you can select any resampling method for a given raster there are some restrictions on which methods are valid for certain field and band combinations. Currently, "Classifed" and "ImagePalette" fields support nearest neighbour only. "Image" field type support nearest neighbour and bi-linear (default) and "Continuous" fields support all methods.

How to enable the resampling methods in Mapinfo Pro

This feature, can be enabled in the Raster Preferences dialog. In the Back Stage area (the "Pro" tab)
> Options > MapInfo Pro Advanced-Preferences) by first checking the "Enable Block Access" check-box and then choosing one of the Resample Display Methods. We suggest using Cubic Spline (Global) for the majority of continuous data types. To turn off/disable this feature for a specific raster file you can use the Advanced Color properties dialog to set More Options - Display Resampling Method = None. If you wish to disable this feature for all raster files, then simply uncheck the "Enable Block Access" option on the Raster Preferences Display Tab.

Enhanced Rendering

These new options have been added to the 15.2.2 64bit patch release as a "Technical Preview" feature. We think you will like the visualization improvements offered by this new capability but we are still in the process of making this feature even better.

Article by Mahima Relan, Associate QA Engineer
When not writing articles for "The MapInfo Pro", Mahima works as Quality Assurance Engineer on the raster capabilities in MapInfo Pro Advanced. When not working she likes to dance, swim and watch nature's beauty.